I adopted two pets this year from the SPCA that were abused before I adopted them.
My dog, Pepper, has more emotional scars. She couldn't stand being scolded at first and she still freaks out when she gets into trouble (which is quite often). She couldn't stand being left alone or being left outside for too long. She's gotten much better; she doesn't fear that we're going to hit her when we scold her and she doesn't mind spending some time by herself.
I also bought a cat that was abused by his previous owner. Ben was run over by a car in his old owner's care, wasn't give proper medical care and neglected so badly that when he was taken to the SPCA he looked like a six month old cat but in reality was over a year. He also had developed an upper respiratory infection and had a case of ear mites. Since his old injuries didn't heal correctly he has a permanent limp and a crooked tail. He has to take medication for the rest of his life but he is finally healthy and happy. Fortunately, the limp doesn't hold him back. If anything he is the most mischevious and active cat I've ever had. With him I play it by year and enjoy all the time I have with him because I don't know how long it will be until arthritis develops in his hips.
It upsets me beyond belief that people abused these animals especially because I have come to know them as the sweetest, loveliest animals.